The present invention is directed to a foot control mechanism for a dental apparatus, wherein an essentially plate-shaped and horizontally-aligned actuation member is present on which the foot of an operator can be placed overall and that, for triggering a switch or control function, the member can be brought from a neutral position into at least two different switching positions directly opposite from one another.
Pending U.S. application Ser. No. 07/694,634, which issued as U.S. Pat. No. 5,300,926 on Apr. 5, 1994 and claims priority from European Application 90108740.3 that was published as European Published Application 0 455 852, discloses a foot control mechanism wherein the pedal or foot support pivots or rotates around a horizontal axis and also can be pivoted or rotated around a vertical axis extending perpendicular to the horizontal axis. Although this type of foot control mechanism has certain advantages over other foot control mechanisms, whose pivot points lie in the region of the tip of the toes or the heel, a holding of the foot support or pedal in a neutral, quiescent position represents a certain problem area, because holding of the pedal in this neutral position can only be accomplished by the user exercising care and muscle control. The operator's foot must always be positioned in a beneficial position over the rotational axis and must also be held in this position during operation in order to always assure a more or less relaxed foot position. Variable heel stops or detents would also have to be provided in order to take into consideration different shoe sizes for the operator. These variable heel stops, however, would deteriorate from the manipulability and the ease of operation.
U.S. Pat. No. 2,762,891, whose disclosure is incorporated herein by reference thereto, discloses a foot switch that contains an actuation element that is fashioned as a pedal and is obliquely placed in the initial position. The pedal on which the foot of the operator can be planarly placed has a seating part in the region of the heel that is intended to lend the foot a reliable held. The pedal is pressed against the detent in an obliquely residing initial position on the-basis of an approximately centrally placed compression spring. The pedal can, thus, be tilted around a horizontal axis approximately placed in the lower third of the length of the foot switch and close to the heel. Thus, the pedal is capable of being tilted opposite the force of the compression spring until the additional stop or detent is reached. In its upper third, the pedal contains a roller level that can roll on a curved path or cam that proceeds concentrically relative to the midpoint of the housing of the foot switch. The cam is secured to a part mounted for rotation on a vertical axis, which is, in turn, coupled to a potentiometer for varying the speed of the dental motor. A swivel motion of the above-mentioned swivellable part is initiated with the tilting of the actuation element and, thus, an adjustment of the potentiometer is achieved. This device would enable having a control of the speed of a motor in one direction and also a control of the speed in the opposite direction.
In this known foot switch, the pedal cannot be brought from a neutral position into two operating positions that are opposite to one another. It can merely be moved from one final position in one direction until the second final position is reached.